You can run jolly Gatr to creep things like Lucario before DD, but you miss out on a lot of other OHKOs that are crucial, and the speed gained along with one Dragon Dance (at 382 with Adamant, 420 with Jolly I blv) only hits a few more scarfers that you really shouldn't be trying to sweep with Gatr anyways (or that rarely run jolly scarf anyways like Dragonite). In the past, Agility sets were experimented with, but these were even inferior to SD + Aqua Jet variants simply because of the damage being so crucial. Gatr's bulky but not Rhyperior bulky where he only needs speed to kill things. Adamant is generally the best for these reasons since you're either doing Aqua Jet+SD, or DD+3 attacks. This croc is meant to come in like a wrecking ball and leave nothing standing.